1. Field of the Invention
This invention relates to a charging and exposure section in an electrophotographic apparatus intended for facilitating provision of retrieval marks, detection of the condition of exposure and control of the quality of recorded picture images.
2. Description of the Prior Art
An electrophotosensitive member is a laminate formed by coating a layer of an electrical conductive material on a base of an electrical insulating material and then coating a layer of a photoconductive, electrical insulating material on the conductive layer. It is one of advantages of an electrophotographic apparatus utilizing such an electrophotosensitive member for recording that recorded picture image data can be readily reproduced. Also, because of such a property of the electrophotosensitive member to have no sensitivity to light before being charged, the electrophotographic apparatus of the kind above-described is advantageous in many aspects over a conventional recording system using the known silver halide photosensitive material for recording, and it is finding many practical applications in various fields making the most of these advantages.
However, prior art electrophotographic apparatus proposed hitherto have been defective in that, in the recording of picture image data on electrophotosensitive members, the condition of charging and development tends to be subject to a change when, for example, the toner is deteriorated, the charging unit is fouled or the power supply voltage fluctuates. This is because, in such an event, the condition of recording picture image data on the electrophotosensitive members cannot be maintained constant, resulting in a non-uniform quality of reproduced picture images. Thus, even when the picture image data may not be reproduced in the optimum mode due to, for example, mal-operation or failure of either the charging unit, exposing unit or developing unit, the apparatus operator who is not aware of the presence of such trouble will continue the recording operation on one electrophotosensitive member after another.
On the other hand, in the case of utilization of the electrophotosensitive member as a microfilm capable of carrying records of many data thereon, it is convenient to record a retrieval mark corresponding to each of the recorded data on the electrophotosensitive member. According to one of the known methods for recording such a retrieval mark on the electrophotosensitive member, a marking corresponding to this retrieval mark is formed on, for example, a table supporting an original, so that this marking is recorded together with the information of the original on the electrophotosensitive member. However, according to the above method, there is a possibility that the marking is hidden by the original and cannot be recorded due to the carelessness of the apparatus operator. Therefore, it is customary to previously print the retrieval mark on the electrophotosensitive member. In such a case, an additional step of printing the retrieval marks on the electrophotosensitive member is required, resulting in a defect that the cost of the elctrophotosensitive member increases inevitably. Further, because of the fact that the retrieval marks are printed at intervals of a pre-set constant distance therebetween, the interval between the retrieval marks does not match the interval between recorded picture image data when the electrophotosensitive member is used in another electrophotographic apparatus in which the size of frames and the interval between the frames are different from the present interval between the retrieval marks.